1. Field of the Invention
The present invention relates to apparatus for purifying contaminated liquids and more particularly to apparatus for electrochemical purification of contaminated liquids.
The invention may be employed for purifying liquids contaminated with organic substances, mechanical suspensions, surfactants, and the like.
The invention is particularly useful for purifying liquids contaminated with polymers and petroleum products, such as waste water containing oils and greases.
2. Description of the Prior Art
Of all the known devices for purifying contaminated liquids, the widest and ever increasing application has recently been found by apparatus for electrochemical purification of liquids, in particular those where liquid is purified by the electroflotation and electrocoagulation methods, which is due to their high performance capabilities.
Apparatus are known where the electrochemical liquid purification process is accomplished either periodically, i.e. in batches, or continuously. The latter appear to be more promising. Such apparatus ordinarily comprise a settling chamber communicating with an electroflotation or electrocoagulation chamber fitted with electrodes. The apparatus comprising an electrocoagulation chamber with soluble electrodes, where also flotation is accomplished, will be discussed hereinafter. The highest economic efficiency and purification rate are offered by the apparatus wherein contaminated liquid is mixed with the electrode dissolution products in the electrocoagulation chamber above the electrodes, since this prevents fouling the electrode surface by impurities contained in the contaminated liquid. For example, an apparatus for electrochemical purification of waste water (USSR Inventor's Certificate No. 644,738) comprises a settling chamber with outlet pipes to discharge purified liquid and sludge, which settling chamber communicates with an electrocoagulation chamber installed therewithin and having in its bottom part a system of soluble electrodes and an inlet pipe to feed electrolyte.
A serious disadvantage of this apparatus is that the degree of purification of the contaminated liquid falls as the concentration of impurities in the liquid increases. The degree of liquid purification can be upgraded by increasing the current density at the electrodes, but this way, apart from a higher consumption of both the power and the electrodes, will result in a poor stability of the liquid purification quality, since a liquid purified to a degree below the specified one, having passed the settling chamber, is discharged from the apparatus.